This invention relates to magnetic recording heads for recording and reproducing high frequency signals and, in particular, to magnetic recording heads that do not generate ficticious output noise.
A prior art magnetic recording head 47 is shown in FIG. 1 and is formed of two opposed thin magnetic members 42 and 42' having thin magnetic layers 43 and 43' angularly disposed thereon. Magnetic members 42 and 43 are coupled using an adhesive glass 44 with a magnetic gap 9 formed therebetween. Recording signals are introduced parallel to magnetic gap 9 and are subject to an azimuth loss as a consequence of the angle 0 between thin magnetic layers 43 and 43' and magnetic members 42 and 42' which creates a magnetic discontinuous space 41 as described in Japanese Patent Laid-Open Application No. 425906/85. A fictitious output or noise is generated by the azimuth loss from magnetic discontinuous space 41.
An output signal waveform as a function of time for a single input signal reproduced by a magnetic recording head of the type shown in FIG. 1 is shown in FIG. 2. An output signal corresponding to the original input signal is indicated as a peak 39 with fictitious outputs or noise being generated both before and after the original output as indicated by peaks 40 and 40'. The fictitious outputs or noise indicated by peaks 40 and 40' cannot be entirely eliminated using prior art recording head constructions.
In particular, when recording head 47 of FIG. 1 is used in a magnetic disk drive, the inner and outer cylinders have different radii and therefore different curvatures. Fictitious outputs or noise signals are generated as a function of the radii of the inner and outer cylinders and are one disadvantage of the structure.
Furthermore, the thickness of the thin magnetic layers in prior art magnetic recording heads affects the width of the recording signals and is generally about 20um. It takes about 20 hours to form a 20um thick magnetic layer by sputtering, which is a disadvantage of the manufacturing process. Additionally, the thicker the thin magnetic layers, the greater the stress and the greater the possibility that the layers will peel off and decrease the manufacturing yield.
These structure also are not durable due to the relative thickness of the thin magnetic layers. When the layers are brought into direct contact with a recording medium, material is removed from the thin magnetic layers and the recording medium or other portions of the magnetic head are injured as a result. Removal of material from the thin magnetic layers changes the width of the magnetic gap. However, it is important to accurately control the width of the magnetic gap since the magnetic gap has a width precisely equal to the width of the recording signal. Removal of material from the thin magnetic layer therefore results in an increased fictitious output or noise. Finally, the structure has assembly difficulties and a low manufacturing yield due to the necessity of using two thin magnetic layers to form the magnetic gap.
Accordingly, it is desirable to provide an improved magnetic recording head which eliminates these problems associated with prior art devices and eliminates fictitious output noise.